To investigate the effects of 2-(4-methoxycarbonyl-2-tetradecyloxyphenyl)carbamoylbenzoic acid (CX09040) on protecting pancreatic β cells, the β cell dysfunction model mice were induced by injection of alloxan into the caudal vein of ICR mice, and were treated with compound CX09040. Liraglutide was used as the positive control drug. The amount and the size of islets observed in pathological sections were calculated to evaluate the β cell mass; the glucose stimulated insulin secretion (GSIS) test was applied to estimate the β cell secretary function; the oral glucose tolerance test (OGTT) was taken to observe the glucose metabolism in mice; the expressions of protein in pancreas were detected by Western blotting. The effects on the target protein tyrosine phosphatase 1B (PTP1B) were assessed by the PTP1B activities of both recombinant protein and the intracellular enzyme, and by the PTP1B expression in the pancreas of mice, separately. As the results, with the treatment of CX09040 in alloxan-induced β cell dysfunction mice, the islet amount (P<0.05) and size (P<0.05) increased significantly, the changes of serum insulin in GSIS (P<0.01) and the values of acute insulin response (AIR, P<0.01) were enhanced, compared to those in model group; the impaired glucose tolerance was also ameliorated by CX09040 with the decrease of the values of area under curve (AUC, P<0.01). The activation of the signaling pathways related to β cell proliferation was enhanced by increasing the levels of p-Akt/Akt (P<0.01), p-FoxO1/FoxOl (P<0.001) and PDX-1 (P<0.01). The effects of CX09040 on PTP1B were observed by inhibiting the recombinant hPTP1B activity with IC50 value of 2.78x 10(-7) mol.L-1, reducing the intracellular PTP1B activity of 72.8% (P<0.001), suppressing the PTP1B expression (P<0.001) and up-regulating p-IRβ/IRβ (P<0.01) in pancreas of the β cell dysfunction mice, separately. In conclusion, compound CX09040 showed significant protection effects against the dysfunction of β cell of mice by enlarging the pancreatic β cell mass and increasing the glucose-induced insulin secretion; its major mechanism may be the inhibition on target PTP1B and the succedent up-regulation of β cell proliferation.
Alloxan ; Animals ; Benzoates ; pharmacology ; Biological Assay ; Disease Models, Animal ; Glucose ; metabolism ; Glucose Tolerance Test ; Insulin ; secretion ; Insulin Resistance ; Insulin-Secreting Cells ; drug effects ; Liraglutide ; pharmacology ; Mice ; Mice, Inbred ICR ; Molecular Weight ; Pancreas ; drug effects ; enzymology ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; antagonists & inhibitors ; Signal Transduction

This study is to evaluate the effects of the metformin (Met) on β cell function of diabetic KKAy mice. Female diabetic KKAy mice selected by insulin tolerance test (ITT) were divided randomly into two groups. Con group was orally administered by gavage with water, Met group with metformin hydrochloride at a dose of 0.2 g x kg(-1) for about 12 weeks. ITT and glucose tolerance tests (OGTT) were determined. Beta cell function was assessed by hyperglycemic clamp. Pancreatic biochemical indicators were tested. The changes of gene and protein expression in the pancreas and islets were also analyzed by Real-Time-PCR and immunostaining. Met significantly improved glucose intolerance and insulin resistance in KKAy mice. Fasting plasma glucose and insulin levels were also decreased. In addition, Met markedly increased glucose infusion rate (GIR) and elevated the Ist phase and maximum insulin secretion during clamp. It showed that Met decreased TG content and iNOS activities and increased Ca(2+) -Mg(2+)-ATPase activity in pancreas. Islets periphery was improved, and down-regulation of glucagon and up-regulated insulin protein expressions were found after Met treatment. Pancreatic mRNA expressions of inflammation factors including TLR4, NF-κB, JNK, IL-6 and TNF-α were down-regulated, p-NF-κB p65 protein levels also down-regulated by Met. And mRNA expressions of ion homeostasis involved in insulin secretion including SERCA2 and Kir6.2 were up-regulated by Met. Met increased SIRT5 expression level in pancreas of KKAy mice under the hyperglycemic clamp. These results indicated that chronic administration of Met regulated pancreatic inflammation generation, ion and hormone homeostasis and improved β cell function of diabetic KKAy mice.
Animals ; Blood Glucose ; Diabetes Mellitus, Experimental ; drug therapy ; Down-Regulation ; Female ; Glucose Tolerance Test ; Homeostasis ; Inflammation ; drug therapy ; Insulin ; secretion ; Insulin Resistance ; Insulin-Secreting Cells ; drug effects ; Interleukin-6 ; metabolism ; Metformin ; pharmacology ; Mice ; NF-kappa B ; metabolism ; Pancreas ; drug effects ; Tumor Necrosis Factor-alpha ; metabolism

This study is to evaluate beta cell function and investigate the mechanism of impaired pancreatic islet beta cell function in monosodium glutamate (MSG) obese rat with insulin resistance, an animal model of metabolic syndrome. Insulin tolerance test was used to screen MSG obese rats with insulin resistance. Blood concentrations of glucose, triglyceride, total cholesterol and insulin were determined. Beta cell function was assessed with hyperglycemic clamp technique. The morphological alterations in pancreas and changes of islet beta cell mass were evaluated by hematoxylin-eosin (HE) and Gomori aldehyde fuchsin staining. Lipid, oxidative stress relevant factors, nitric oxide (NO) level and activity of ATPase in pancreas and pancreatic mitochondrial were tested. The MSG obese rats with insulin resistance could be validated as a typical metabolic syndrome animal model possessing increased fasting plasma triglycerides and insulin (P < 0. 001), markedly decreased weight indices of pancreas and impaired glucose-stimulated insulin secretion. Hematoxylin-eosin (HE) and Gomori aldehyde fuchsin staining showed increased adipocytes and fibroplasia deposition in pancreas and reduced beta cell mass. The increased contents of triglyceride and NO level, the decreased SOD levels and activities of total ATPase (P < 0.001), Na+-K+-ATPase (P < 0.001) and Ca2+-Mg2+-ATPase (P < 0.01) were observed in pancreas and its mitochondria versus normal rat. The study demonstrates that accumulation of lipids in pancreas could lead to increased systemic indicators of inflammation, such as NO, which may influence the activities of several kinds of ATPase in cell membranes and interfere the ion transport, substance metabolism and energy production in pancreas. Finally the MSG obese rats characterized with metabolic syndrome displayed an impairment of beta cell function.
Adenosine Triphosphatases ; metabolism ; Animals ; Blood Glucose ; metabolism ; Insulin Resistance ; Insulin-Secreting Cells ; pathology ; secretion ; Male ; Malondialdehyde ; metabolism ; Metabolic Syndrome ; chemically induced ; metabolism ; pathology ; Mitochondria ; metabolism ; Nitric Oxide ; metabolism ; Obesity ; chemically induced ; metabolism ; pathology ; Organ Size ; Pancreas ; metabolism ; pathology ; Rats ; Rats, Wistar ; Sodium Glutamate ; Superoxide Dismutase ; metabolism ; Triglycerides ; blood

BACKGROUNDThe pathogenesis of acute pancreatitis is complex and largely unclear. The aim of this study was to explore the relationship between modes of cell death in pancreatic acinar cells, the release of cell contents and the inflammatory response of macrophages.

METHODSOur experiment included four groups: group A (the control group), group B (AR42J cells overstimulated by caerulein), group C (AR42J cells treated with lipopolysaccharide and caerulein), and group D (AR42J cells treated with octreotide and caerulein). Apoptosis and oncosis, and the release of amylase and lactate dehydrogenase (LDH) from AR42J cells were detected. Rat macrophages were stimulated by 1 ml supernatant of culture medium of AR42J cells. Finally, NF-kappaB activation and TNF-alpha and IL-1beta secretion by macrophages were detected.

RESULTSOncotic cells in group C increased while apoptotic cells decreased (P < 0.05); cells in group D had the inverse reaction. The release of amylase and LDH changed directly with the occurrence of oncosis. The transcription factor NF-kappaB was activated and secretion of TNF-alpha and IL-1beta were significantly higher in group C than in group B (P < 0.05); in group D, these actions were significantly lower than in group B (P < 0.05). This trend was in line with changes in amylase and LDH production.

CONCLUSIONThere is a close relationship between modes of pancreatic acinar cell death, the release of cell contents and the inflammatory reaction of macrophages.

Amylases ; secretion ; Animals ; Apoptosis ; Interleukin-1beta ; secretion ; L-Lactate Dehydrogenase ; secretion ; Macrophage Activation ; Male ; NF-kappa B ; metabolism ; Pancreas ; pathology ; Rats ; Rats, Wistar ; Tumor Necrosis Factor-alpha ; secretion

OBJECTIVETo study the changes of canine Oddi sphincter (SO) function after pancreas transplantation with bladder drainage and the effect on the graft function.

METHODSNormal canine SO, transplant canine SO and canine SO in vitro manometry were performed by triple lumen catheter. At the same time, pancreas endocrine and exocrine function after transplantation were determined. After transplantation, anti-reflux function of graft SO was also measured.

RESULTSEndocrine and exocrine function of all the transplanted dogs showed that pancreas graft function was good. Basal pressure of SO in control group was (18.5 +/- 2.8) mm Hg (1 mm Hg = 0.133 kPa). The contraction frequency was (9.7 +/- 1.5) per min, the contraction amplitude was (47.1 +/- 5.5) mm Hg, the motility index was (236 +/- 56). After transplantation, basal pressure increased to (27.8 +/- 2.8) mm Hg, frequency increased to (13.1 +/- 1.9) per min, amplitude decreased significantly to (8.3 +/- 1.8) mm Hg. There was no significant difference of motility index. Basal pressure of SO in vitro increased significantly to (37.2 +/- 5.1) mm Hg. Phasic contraction was not absent. After transplantation, the pressure in the bile duct residual did not increase in accordance with the increase of bladder pressure.

CONCLUSIONSAfter pancreas transplantation with bladder drainage, Basal pressure and frequency of canine SO could increase while amplitude could decrease, which provide the anti-reflux function of graft SO and may serve as an obstacle to pancreatic juice flow.

Animals ; Dogs ; Drainage ; methods ; Female ; Male ; Pancreas Transplantation ; methods ; physiology ; Pancreatic Juice ; secretion ; Sphincter of Oddi ; physiology ; Transplantation, Homologous ; Urinary Bladder ; surgery

BACKGROUND/AIMS: Pancreatic acini of streptozotocin (STZ)-induced diabetic rats release amylase less than normal acini on cholecystokinin (CCK) stimulation. Pancreatic enzyme secretion has been closely related to the intracellular calcium concentration ([Ca2+]i) of the acinar cell. In the present study, sequential changes of the intracellular calcium signal which probably underlie the altered enzyme secretion in response to CCK-8 were investigated using pancreatic acini from diabetic rats. METHODS: Diabetic rats were prepared by single intravenous injection of STZ (70 mg/kg). Stimulating experiments with CCK-8 were performed 7 days later. Pancreatic acini were isolated by collagenase digestion. Amylase release and [Ca2+]i were measured by colorimethod and calcium imaging, respectively. The geometry of intracellular calcium signal was analyzed. RESULTS: Normal acini exhibited concentration-dependent [Ca2+]i increase and regular oscillatory calcium signal on CCK-8 stimulation. Amylase release was also concentration-dependent. However, diabetic acini showed significantly less [Ca2+]i increase, prolonged time to peak [Ca2+]i, decreased calcium spikes number, and decreased amylase release compared with normal acini. The decreased [Ca2+]i in diabetic acini was restored significantly by insulin treatment. CONCLUSIONS: Relatively decreased amylase release in diabetic pancreatic acini in response to CCK, appears to be associated with altered calcium signal due to insulin deficiency.
Amylases/*secretion ; Animals ; Calcium Signaling/*drug effects ; Diabetes Mellitus, Experimental/*physiopathology ; Pancreas/cytology/metabolism/*secretion ; Rats ; Rats, Sprague-Dawley ; Sincalide/*pharmacology

AIMTo know the effect of cysteamine on the pancreatic secretion and enzyme activity in geese.

METHODSEight adult geese fitted chronic pancreatic and duodenal cannulas were used to evaluate the effect of cysteamine (CS) on the pancreatic secretion and enzyme activity. The experiment was consist of control and treated phase. CS was added in the diet at the dosage of 100 mg/kg bw on the first day of treated phase. The birds were free fed at daytime (8:00-20:00) and fasted at nighttime (20:00-8:00). The pancreatic juice samples were collected continuously for three days in each phase.

RESULTSCS increased the average rate of pancreatic secretion by 240.16% (P < 0.01), in which that of daytime was elevated by 234.45% (P < 0.01), while that of nighttime elevated by 253.70% (P < 0.01). The secretion volume at daytime was more than that of night. CS increased trypsin activity by 49.05% (P < 0.01), whereas lipase and amylase activity was reduced by 25.44% (P < 0.01) and 21.95% (P < 0.01) separately. The one hour total activity of trypsin, lipase and amylase were elevated by 406.88% (P < 0.01), 153.58% (P < 0.01) and 166.59% (P < 0.01) respectively. Ratios of pancreatic secretion were different between day and night.

CONCLUSIONThese results indicate that CS can affect the pancreatic juice secretion and pancreatic enzyme activity by depleting the somatostatin, so that benefits to improve the digestive foundation and supply more nutrition for quickly growing in geese.

Animals ; Cysteamine ; pharmacology ; Geese ; physiology ; Pancreas ; drug effects ; enzymology ; secretion ; Pancreatic Juice ; secretion ; Pancreatin ; metabolism

In pancreatic acinar cells Ca(2+)-dependent secretagogues promote the fusion of zymogen granules (ZG) with the apical plasma membrane (PM) and exocytosis of digestive enzymes. In addition to exocytotic fusion complexes between SNARE proteins in the ZG membrane (ZGM) and the apical PM, enzyme secretion elicited by Ca(2+)-dependent secretagogues requires cytosolic Cl and K+ and is inhibited by blockers of Cl- and K+-channels. We have identified a Cl-conductance activated by ATP, and a K+-conductance (with properties similar to ATP-sensitive K+-channels), regulated by the granule matrix protein Zg-16p in the ZGM. Both conductances are inversely regulated by a 65-kD mdr1 gene product. We have also identified a novel Ca(2+)-activated anion conductance in ZGM, the Ca(2+)-sensitivity of which increases 50-fold when Cl is replaced by 1. This conductance is blocked by micromolar H2-DIDS or DTT, reminiscent of a family of epithelial Ca(2+)-activated Cl -channels (CaCC). Expression of a CaCC in exocrine pancreas has been confirmed by RT-PCR analysis, and by immunoblotting and immunogold labeling of ZG membranes. These data suggest that ion channels in the ZGM are essential elements in pancreatic exocytosis.
Animal ; Chloride Channels/metabolism* ; Chloride Channels/genetics ; Exocytosis/physiology* ; Gene Expression/physiology ; P-Glycoprotein/metabolism ; P-Glycoprotein/genetics ; Pancreas/secretion* ; Pancreas/cytology ; Potassium Channels/metabolism* ; Potassium Channels/genetics ; Secretory Vesicles/secretion ; Secretory Vesicles/metabolism* ; Support, U.S. Gov't, P.H.S.

No abstract available.
Exocytosis/physiology* ; Pancreas/secretion ; Pancreas/physiology* ; Pancreas/cytology*

Since GABA and its related enzymes had been determined in beta-cells of pancreas islets, effects of GABA on pancreatic exocrine secretion were investigated in the isolated perfused rat pancreas. GABA, given intra-arterially at concentrations of 3, 10, 30 and 100 microM, did not exert any influence on spontaneous or secretin (12 pM)-induced pancreatic exocrine secretion. However, GABA further elevated cholecystokinin (10 pM)-, gastrin-releasing peptide (100 pM)- or electrical field stimulation-induced pancreatic secretions of fluid and amylase, dose-dependently. The GABA-enhanced CCK-induced pancreatic secretions were completely blocked by bicuculline (10 microM), a GABAA receptor antagonist but not affected by saclofen (10 microM), a GABA(B) receptor antagonist. The enhancing effects of GABA (30 microM) on CCK-induced pancreatic secretions were not changed by tetrodotoxin (1 microM) but partially reduced by cyclo-(7-aminoheptanonyl-Phe-D-Trp-Lys-Thr[BZL]) (10 microM), a somatostatin antagonist. In conclusion, GABA enhances pancreatic exocrine secretion induced by secretagogues, which stimulate enzyme secretion predominantly, via GABA(A) receptors in the rat pancreas. The enhancing effect of GABA is partially mediated by inhibition of islet somatostatin release. GABA does not modify the activity of intrapancreatic neurons.
Amylases/metabolism ; Animal ; Baclofen/pharmacology ; Baclofen/analogs & derivatives* ; Bicuculline/pharmacology ; Cholecystokinin/metabolism ; Dose-Response Relationship, Drug ; Electric Stimulation ; GABA/pharmacology* ; GABA Antagonists/pharmacology ; Gastrin-Releasing Peptide/metabolism ; Hormones/pharmacology ; In Vitro ; Pancreas/secretion* ; Pancreas/enzymology ; Pancreas/drug effects* ; Rats ; Receptors, GABA-A/metabolism ; Secretin/metabolism ; Somatostatin/pharmacology ; Tetrodotoxin/pharmacology